Oxytetracycline accumulation in the macroalgae Ulva: Potential risks for IMTA systems.

Area of Science:

• Environmental Science
• Aquatic Toxicology
• Marine Biology

Background:

• Integrated Multitrophic Aquaculture (IMTA) systems aim to reduce environmental impacts.
• Co-cultured species in IMTA may accumulate pharmaceuticals like oxytetracycline (OTC).
• Potential human consumption risks from pharmaceutical accumulation in farmed species require investigation.

Purpose of the Study:

• To assess the accumulation and degradation of OTC in the seaweed Ulva.
• To determine if Ulva influences OTC degradation in seawater.
• To evaluate the potential risks of OTC accumulation in Ulva for human consumption.

Main Methods:

• Exposure of Ulva to two realistic OTC concentrations (0.040 and 0.120 mg/L).
• Monitoring of OTC degradation rates in seawater with and without Ulva.
• Quantification of internal OTC concentrations in Ulva tissues over time.
• Assessment of Ulva growth and physical condition.

Main Results:

• OTC degradation in seawater was concentration-dependent but not affected by Ulva presence.
• Ulva assimilated significant amounts of OTC, with internal concentrations up to 108.6787 ng/g WW.
• OTC levels in Ulva decreased over time but remained below the Maximum Residue Limit for fish (100 μg/kg).
• High OTC concentrations stimulated Ulva growth initially but also caused signs of decay.

Conclusions:

• Ulva effectively assimilates OTC from aquaculture water.
• OTC accumulation in Ulva, at tested levels, may not pose an immediate food safety risk concerning fish residue limits.
• Further research is needed to understand the long-term effects of OTC on Ulva and its implications in IMTA systems.